4 ms·
Maybe mercury is different (though I doubt it), but current electric propulsion sats use nothing like that much mass. A Boeing 702 HP (a big GEO comsat) Xenon p
by jccooper 5y ago
Maybe mercury is different (though I doubt it), but current electric propulsion sats use nothing like that much mass. A Boeing 702 HP (a big GEO comsat) Xenon propulsion system has a capacity for 266kg of Xenon; uses about 5kg per year for station keeping. Constellation sats are usually smaller; a Starlink sat is about 260kg total. Dunno how much krypton they carry, but probably in the low 10s of kg each.
- sjburt 5y agoI think the concern was that some organizations were considering big low-altitude constellations. Once you go below 400km or so the drag increases quite a bit so the idea would be to use near-constant thrust similar to GOCE or SLATS. And there was at least one vendor (Apollo Fusion) proposing a mercury thruster, although I think they have backed off on that. It would have had about 3x the impulse per volume and 2x the impulse per mass of xenon. I think banning it now is wise, if any small operators had started using it it would have been hard to block it for a megaconstellation and it was very clear that anything release in VLEO would be coming back into the atmosphere. Right now there are no users so you aren't really penalizing anyone.
- deleted 5y ago[deleted]
- rsynnott 5y agoIt mentions communications _networks_. If you have 10,000 satellites with 10kg propellant each, there's your hundred tonnes of propellant.
- ars 5y agoI got it from Wikipedia: "The Dawn spacecraft broke the record, with a velocity change of 11.5 km/s (41,000 km/h), though it was only half as efficient, requiring 425 kg (937 lb) of xenon." I rounded up to one ton, since we're only trying to figure out order of magnitude.
- skykooler 5y agoDawn is an interplanetary probe, though, and requires orders of magnitude more fuel than satellite constellations. For a more realistic figure, the Starlink satellites are fueled with about 5 kg of krypton.
- Arainach 5y agoStarlink alone has launched more than 2,000 satellites already and plans a total of at least 12,000. That's a lot of fuel - and that's just one constellation.
- krisoft 5y ago> That's a lot of fuel - and that's just one constellation. Is that a lot of fuel? 5kg times 12000 is about 60 tonne. That's the weight of two big truck approximately. In which sense is that a lot of fuel? And besides krypton is a noble gas, it doesn't react with anything.